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METAMORPHIC ROCKS- “MORPHED” FROM SEDIMENTARY OR IGNEOUS ROCKS. 6.3 Lecture Notes. Agents of Metamorphism. Heat causes rocks to expand & mineral bonds weaken or break. Once broken, they can form new minerals!. Effects:. Heat. Geothermal G radient (increasing temps within Earth) Magma. - PowerPoint PPT Presentation
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Agents of MetamorphismHeat
6.3 Lecture Notes
Heat causes rocks to expand & mineral bonds weaken or break. Once broken, they can form new minerals!1. Geothermal Gradient (increasing temps within
Earth)
2. Magma.
Effects:
Sources:
METAMORPHIC ROCKS- “MORPHED” FROMSEDIMENTARY OR IGNEOUS ROCKS
Chemically Active FluidsIons in fluids can mix with ions in minerals & actas a “seed” for new mineral growth.
1. Ionic solutions deep within Earth.
2. Ionic solutions in heated water, near magma chambers.
Effects:
Sources:
PressurePressure compacts rocks & can break ionic bonds.This creates more-compact mineral structures.
1. Weight of overlying rocks deeper in Earth.
2. At convergent boundaries.
3. Along fault lines.
Effects:
Sources:
Types of Metamorphism
1. Heat 2. Pressure
When a meteorite hits Earth, extreme pressure& heat alter rocks that are hit.
Primary Agents:
Describe:
Impact
DynamicPressure
Pressure changes rock structure along a fault line as rocks are crushed.
Primary Agents:
Describe:
RegionalPressure, temp, chemically active fluids
All 3 agents together can cause huge areas of rocks to metamorphose. Example: Mountain Building.
Primary Agents:
Describe:
ContactHeat
A tremendous heat sources contacts a pre-existingrock. Example: Igneous intrusions.
Primary Agent:
Describe:
Rock texture & minerals usually change.Characterisitcs:
BurialPressure
As rock gets buried deep in Earth, equal pressurescompress it from all sides.
Primary Agent:
Describe:
No banding pattern compared to Sedimentary rocks that get buried and compressed.
Characteristics:
Burial metamorphic Compressed Sedimentary
RecrystallizationThe growth of new mineral grains are biggerthan the original grains of minerals.
Describe:
Types of Change
Occurs when grains move closer together &reduce pore size (spaces between grains) due toIncreased pressure.
Describe:
Compaction
Under pressure, grains of rocks become aligned parallel to each. This changes the texture.
Describe:
Foliation